Demon's Desire (A Hearts of the Fallen Novel) by Kendra Leigh Castle:
He's as dark and dangerous as the storms he once commanded…and she can't get him out of her heart.
Dru has spent two thousand years fighting to keep the people of Terra Noctem safe. In all that time, she's only opened her heart to one man, with disastrous results. But when her city takes in a group of renegade Fallen, she finds herself drawn to the brooding and tormented Meresin, despite the fact that he seems to be the least redeemable of them all. When his instability hits a breaking point, Meresin's only chance at survival is a perilous journey into a place from which few ever return. What he never expected was that confronting his demons would mean risking not only his future, but Dru's as well...and that one stubborn vampire might give him back not just hope…but his heart.